The considerable heat to which a turbojet engine of an airplane engine is subjected provokes thermic dilations and it is a considerable advantage to be able to adjust said dilations so as to in particular avoid any gas leaks and the resultant losses of efficiency. In particular, it is extremely important that the radial play, namely between the external extremities of the mobile vanes of the rotor and the internal ferrule of the stator bearing the fixed vanes for correcting the flow between the mobile vanes, is as small as possible. Two main means exist so as to obtain a satisfactory construction: producing the ferrules with a soft coating at the location in front of which the mobile vanes move so that any possible rubbing of the extremity of the mobile vanes, which would be produced by means of a higher dilation of said vanes, would result in wear of the coating and provoke a shaping of the stator at this location, or producing the stator in such a way that it is possible to have the gas circulate there and be taken from another location of the engine, for example, said gas being taken at a particular temperature and with a flow rate able to produce heating or cooling which governs the dilations of the ferrule and thus its play with the mobile vanes.
There is available a wide number of dispositions able to attain this objective with relative success. In one of the most related conceptions of the invention illustrated by the French patent No 1 003 299, the stator is provided, apart from one outer housing in the shape of a circular ring, with ferrule elements bearing fixed vanes and having the shape of a sector of a circle and merely covering one circumference fraction of the stator. The ferrule elements are juxtaposed in such a way that they are divided into groups, each group extending over the entire circumference of the stator, except for plays which extend between their extremities and which thus separate them. The ferrule elements are rigidly secured to the housing at a central location of the sector. This disposition has the advantage that the dilations of the ferrule elements may be easily adjusted without obtaining internal stresses by virtue of the discontinuity of the elements, but it means that the extremities are no longer supported and guided, which is likely to provoke damaging vibrations and prevents an accurate adjustment of the position of the ferrule elements.